ACTIVITY #11ACTIVITY #11 Light Concentration and the Light Concentration and the

Seasons.Seasons.Did you ever wonder why it is colder in the Did you ever wonder why it is colder in the

winter in Delaware and warmer in the winter in Delaware and warmer in the summer? summer?

What causes the seasons?What causes the seasons? What effect will the What effect will the angle of insolationangle of insolation

have on the amount of energy a particular have on the amount of energy a particular area receives?area receives?

GOALS: In this lab activity, you GOALS: In this lab activity, you will …will …

WDWDUse a flashlight, protractor, and grid paper Use a flashlight, protractor, and grid paper

to do a mathematical analysis of to do a mathematical analysis of decreasing energy values.decreasing energy values.

MAIN IDEASMAIN IDEAS: : The important The important concepts and skills covered in concepts and skills covered in

this activity are …this activity are …WDWD

The The angle ofangle of insolation insolation determines determines the amount of concentrated radiant energy the amount of concentrated radiant energy an area receives from the Sun. an area receives from the Sun.

By decreasing the By decreasing the angle of angle of insolationinsolation, there is a corresponding , there is a corresponding decrease in the amount of energy in a decrease in the amount of energy in a given area. given area.

Light Concentration and the Light Concentration and the SeasonsSeasons

WDWDBackground: Some areas of our planet Background: Some areas of our planet

get more direct and concentrated get more direct and concentrated sunlight during different times of the sunlight during different times of the year. year.

As a result, these areas experience As a result, these areas experience warmer periods we call summer. warmer periods we call summer.

When the Sun’s light is less When the Sun’s light is less concentrated and the days are shorter, concentrated and the days are shorter, these areas experience winter. these areas experience winter.

Light Concentration and the Light Concentration and the SeasonsSeasons

WDWD In this activity, you will calculate the In this activity, you will calculate the

percentage of energy that is received percentage of energy that is received from light transmitted at three different from light transmitted at three different angles.angles.

Purpose:Purpose:WDWD

To determine how the percentage of light To determine how the percentage of light distributed (concentrated) in an area distributed (concentrated) in an area changes with a decreased angle of changes with a decreased angle of insolation.insolation.

Materials (per pair of students):Materials (per pair of students):

FlashlightFlashlight30 cm metric ruler30 cm metric rulercalculatorcalculatorProtractorProtractor90, 60, & 30 degree grid paper90, 60, & 30 degree grid paper

Procedure:Procedure:

Part 1Part 1Using a protractor, hold the flashlight over Using a protractor, hold the flashlight over

the 90 degree grid paper so it is at a the 90 degree grid paper so it is at a distance of 20 cm. distance of 20 cm.

Trace the area directly highlighted by the flashlight’s beam onto the graph paper.

If there is a brighter circle, surrounded by a somewhat dimmer circle, trace only the brightest part.

Shade in the area that is circled on the grid paper.

Procedure:Procedure:

Count the number of grids that are Count the number of grids that are shaded in: shaded in:

(a grid more than ½ shaded counts as 1, a (a grid more than ½ shaded counts as 1, a grid less than ½ counts as 0).grid less than ½ counts as 0).